It is known in the field of dermatology to make use of coal tar preparations in the treatment of certain skin conditions, for example, psoriasis [Hunter J. A. A., Savin J. A. and Dahl M. V., Clinical Dermatology, Blackwell Scientific Publications p.49].
It has also been suggested that essential fatty acids, including evening primrose oil may be used in the treatment of skin conditions such as eczema [see references cited by July Graham, Evening Primrose Oil, Thorsons, pp. 127-128].
Various other compositions are known to be used in the treatment of these and other skin conditions.